I watched the episode, and found it hard to be emotionally moved, at all. Familly Guy has been trucking with cynical and heartless humor for so long that any attempt at showing real emotion and empathy just comes off as hollow to me. It was like, "Hey, let's make a big emotional moment when Brian dies. You know. The kind of emotion people with emotions feel -- it'll kill the audience! I think. But it'll get ratings!"
I suppose, though, that I did feel for Stewie's grief. I'll admit that rang true enough.